Apparatus for severing and recovering submarine cables



3 516 158 J 23 1970 A. FERRENTINO APPARATUS FOR SEVERING-AND RECOVERING SUBMARINE CABLES;

jFiled Feb. 25, 1968 2 Sheets-Sheet 1 INVENTOR ANTONIO FERRENTINO 4 M, 2mm, mAfW ATTORNEYS.

June 23, 1970 A. FERRENTINO 3,516,158

APPARATUS FOR SEVERING-AND RECOVERING SUBMARINE GABLES -Filed Feb. 23, 1968 2 Sheets-Sheet 2 INVENTOR ANTONIO FERRENTINO BY l, Z7: ATTORNEYS.

United States Patent 3,516,158 APPARATUS FOR SEVERING AND RECOVERING SUBMARINE CABLES Antonio Ferrentino, Naples, Italy, assignor to Pirelli S.p.A., Milan, Italy, a corporation of Italy lFiled Feb. 23, 1968, Ser. No. 707,761 Claims priority, appllgcatiopfigtaly, Mar. 13, 1967,

9 Int. Cl. B25f 3/00 US. Cl. 30-434 9 Claims ABSTRACT OF THE DISCLOSURE A grappling hook for submarine cables has two parts united for longitudinal separation along a median plane. Each part has a reservoir for hydraulic fluid and a hydraulically actuated lever for clamping a cable in the throat of the hook. A hydraulically actuated knife blade is pivoted on the grappler part. When the blade is extended the grappler parts can be forcibly separated longitudinally by a hydraulic actuator in the second part with the action of separation causing severance of the cable. Individual grappling cables retrieve the separated parts with the severed cable.

The present invention relates to a device for effecting the recovery of submarine cables laid at great depths and, in particular, to a device which enables the cutting or severing of the cables and the recovery of the two out ends to take place simultaneously.

When the repair of a submarine cable has to be carried out, or a splice is to be made at a point situated at a substantial distance from the shore and at a depth at which it would not be possible for divers to operate, it is necessary to bring to the surface that section of the cable on which said operations are to be carried out.

To this end, it not being thinkable to pick up all the cable laid up to the point envisaged for the repair or splice, the cable is cut in proximity to that point, and the two ends are brought aboard the recovery vessel, where the desired operation is carried out.

To carry out the cutting of the cable, heretofore, a grappler of a particular shape has been used which, once lowered to the bottom where the cable is laid, is dragged with a movement in the transverse direction with respect to the cable until the latter is hooked. The operation of making a satisfactory out has been carried out by mechanical means in those cases where the sectional area of the cable was not too big, or by explosive charges disposed close to the cable.

In the mechanical version the grappler is provided with two cutting jaws which close on the cable as soon as a drawing action is effected from the vessel on the grappler itself. The raising action imparted from the vessel and the reaction due to the weight of the cable provide subsequently the necessary force for the cut.

In the alternative version an explosive charge controlled from the vessel is incorporated in the grappler or is lowered as far as the hooking point by means of a special tool which runs along the cable of the grappler.

Having cut the cable, the two out ends must be recovered. This operation has heretofore been carried out by grappling and lifting on board both the ends, or by hooking, before the operation of cutting, two points of the cable on opposite sides of the cutting point, and anchoring them with appropriate fastening means to two floating buoys; following the cutting operation, the two out ends remain anchored to the buoys and can be recovered one at a time.

The present invention provides a device for carrying out the cutting of submarine cables, which can be used Patented June 23, 1970 for cables of any cross section and laid on any bottom, and which accomplishes the immediate simultaneous recovery of the two out ends of the cable.

In accordance with the present invention there is pro-' vided apparatus for severing and recovering submarine cables comprising a grappler formed from two sections each with a hook-shaped throat portion, said sections being provided with means for separably joining one to the other in side-by-side relationship for relative longitudinal separation and with said throat portions cooperating to provide a throat for the grappler, individual cable means secured to each of said sections for manipulating the grappler in a body of water, means carried by each of said sections for obtaining an independent grip on a submarine cable lodged in said grappler throat, and means for simultaneously severing said submarine cable and separating said sections along a common plane.

According to an embodiment of the invention, the means for gripping the cable in the two sections of the grappler include two levers, each of which is pivoted centrally in a corresponding one of the said two sections of the grappler. Said levers have one end appropriately curved for acting, together with the throat of the respective section of the grappler, as a vise for the cable. The opposite ends of the levers, projecting at the side of the grappler opposite the hook, are connected to hydraulic means associated with the corresponding section of the grappler and arranged to actuate the respective lever.

The arrangement for accomplishing the cutting of the cable and the simultaneous separation of the two sections of the grappler advantageously comprises: a first knife edge formed on a blade pivotally joined to a first one of the aforementioned two sections of the grappler in such a manner that the knife edge lies in the middle plane of the grappler when the sections are assembled, said blade having a rear extremity connected with hydraulic means associated with said first section of the grappler; a second knife edge consisting of a concave edge of the second grappler section which lies in said middle plane; and suitable hydraulic means associated with said second section of the grappler for causing relative longitudinal movement between the two sections of the grappler thereby causing the two knife edges to approach each other.

In order to lock the two sections of the grappler together, the blade is provided with a projection or protuberance on its side facing the second of said section, and said second section has a groove or recess complementing said projection. The blade is able to assume, by reason of actuating means connected thereto, two positions. In the first position, the 'blade is withdrawn into the first section of the grappler and the projection with which it is provided is lodged in the groove or recess in the second section. In this manner, mutual displacement of the two sections is prevented. In the other position of the blade its extremity remote from that connected with the actuating means is disposed in a recess against an abutment in the curved extremity of the first section of the grappler. This recess serves to prevent displacement of the blade, i.e., further pivotal movement, during the cutting operation. Also in this position of the blade, the projection with which it is provided is now external to the recess in the second section of the grappler.

The several hydraulic actuating means referred to above may be provided by arranging each section of the grappler with a reservoir filled with hydraulic fluid, for example, oil. The actuating means may consist of electric motors supplied from the ship through the grappler cables and pumps actuated by said motors, all inside the two reservoirs. Pipes for the hydraulic fluid may be connected to the pumps and extend through the walls of the reservoir to hydraulic cylinders or actuators positioned outside the reservoirs and integral with the corresponding sections of the grappler. Pistons sliding in the cylinders under the action of the hydraulic pressure, in this case oil, are connected to the clamping levers and cutting blade by respective connecting rods. Longitudinal movement between the two sections of the grappler is provided by a further bydraulic cylinder and piston, the former being associated with one section of the grappler while the piston protrudes therefrom so as to bear against the other section of the grappler in the longitudinal direction.

While the device is being lowered to the sea bed with the ship in motion, it is desirable that the two cables by which the two sections of the grappler are suspended, do not become entangled. It is therefore necessary to impart to the device a directional stability. To this end it is convenient to make the reservoirs with a flattened form in such a way that they act as fixed rudders. Further, the length and width of the reservoirs are chosen in such a way that the center of hydrostatic thrust of the apparatus is caused to fall on the reservoir side of the center of gravity of the entire device. This buoyancy effect keeps the hook on the bottom when the device is laid.

The invention will be better understood from the following detailed description which is presented with reference to the attached drawings which illustrate by way of example a presently preferred embodiment of the invention. In said drawings:

FIG. 1 shows, in side elevation with portions broken away, the device according to the invention in working position;

FIG. 2 is a front view of the device of FIG. 1;

FIG. 3 shows, in side elevation, the device of FIG. 1 in inoperative position;

FIG. 4 is a front elevation of the device at the end of the cutting operation; and

FIG. 5 is an elevational view of the opposite side of the device of FIG. 1, but with the parts in inoperative position.

Referring now to the drawings, there is shown generally at A and B the two sections which together constitute the grappler. Each section is in the form of a hook which, when brought together side-by-side, confer hook shape to the grappler. Sections A and B are joined to each other by means of longitudinal T-shaped or dovetail guides, generally designated by the reference characters 1 and 2, and consisting of male and female components located, respectively, on the sections B and A.

The sections of the grappler are held suspended from the ship by means of cables 3, 3'. These cables have a dual function of mechanically supporting the sections of the grappler during the grappling operation and of communicating by means of electric conductors which constitute the cores thereof (shown by the broken lines in FIG. 1) electricity to the electric motors mounted in the respective grappler section, as described hereinafter.

The cables 3, 3' are arranged to be paid out from the ship and are provided with ties betwen them every 4 to 5 meters. These ties, over a sufiicient length of the cable, will absorb the forces generated by the difference in tension on the two cables 3, 3 during the operation. The ties will break from the bottom towards the top when the cables, during their successive recovery, are caused to diverge to form the two catenaries.

On board, the two cables 3, 3 are passed over a differential gauge showing the differences, if any, in the cable lengths paid out in the sea. In addition, the difference in tension on the two cables can be indicated by suitable dynamometers associated with the laying winch. This should be apparent from a consideration of the fact that as soon as one cable is paid out more than the other, the grappler will be suspended on the shorter cable which will then support its entire weight.

One side of the grappler is provided with the hook 7. On the opposite side of the grappler, two reservoirs, 4, 4', are mounted, one for each section. These reservoirs are filled with oil for hydraulic purposes. The shape of the reservoirs is flattened, somewhat as shown, so that when the hooks are lowered and trolled by reason of motion of the ship, the reservoirs act as rudders and steer the grappler. In this manner the grappler is compelled to maintain its orientation throughout its descent avoiding any rotation which might cause entanglement of the cables.

The shape and location of the reservoirs 4, 4' have been chosen in such a way that, besides acting as stabilizers during the descent of the grappler, the buoyancy thereof, due to the lower density of the oil contained therein relative to the water, maintains the grappler, at the time it touches the sea bed, with its hook-shaped end lying on said bed and the other extremity elevated by the hydrodynamic thrust upon the reservoirs. The grappler is therefore able to traverse the undulating bed of the sea with only its hook-shaped end in contact therewith.

As mentioned heretofore, the grappler is formed by the two united sections A and B. The reservoirs 4, 4 are mounted on the back of the respective sections. In the reservoir 4, which is associated with the section A, there are, completely immersed in the oil, pumps 8 and 9 and their respective driving motors 10 and 11 (the electric windings of which are insulated with oil-resistant material). The motors are fed from the ship thorugh the cable 3, as previously mentioned.

External to reservoir 4 are disposed, fixed to section A, two cylinders 12 and 13 which are filled with oil and in each of which slides an appropriate piston. The conduits 15 and 16 are connected to pumps 8 and 9, respectively, and, emerging through seals from reservoir 4, connect these same pumps to cylinders 12 and 13.

On actuating the motors, the pumps send oil under pressure to the cylinders and cause movement of the pistons.

Motors, pumps, conduits and other components, identical to those described as being in section A of the grappler, are similarly located in section B and distinguished by the use of prime marks in association with the same reference numerals. These components are best seen in FIG. 5. The principal diflerence between the two sections of the grappler, other than the fact that one is a mirror image of the other, is that in section B the cylinder 13" is located, for a purpose to be described below, in the lateral or offset extension 17' at the upper end (i.e., the end oppoosite the hooked end) as seen in FIG. 2. The lateral extension 17' of section B is accommodated, as shown, in a complementary recess 17 in section A.

In order to compensate for any reduction of the oil volume in the reservoirs due to variation of the hydrostatic pressure or of the temperature, and above all to the flow of oil from the reservoirs to the external cylinders which, due to the creation of a vacuum in the reservoirs, would cause crushing of the same, said reservoirs are provided with an orifice, such as 21, through which the sea water is able to pass to the interior of the reservoirs to compensate for said reduction. An elastic membrane, such as 23, isolates the oil inside the reservoirs from the water which enters through the orifice.

Sections A and B have towards their bottoms or hooked ends two openings or slots 18 and 18' in which two levers 19 and 19, are centrally hinged or pivoted. The end of lever 19 which extends to the rear of section A is pivotally joined to the shaft 20 integral with the piston sliding in cylinder 12. In similar manner lever 19' extends to the rear of section B and is connected to an actuating cylinder 12'. (See FIG. 5.) The forward ends of levers 19 and 19' have a curved profile on the edge facing the throat of the grappler intended to embrace the surface of the cable.

Entirely within section A there is provided, on the edge which mates with section B, between the grooves representing the female parts of guides 1 and 2, a recess 24 in which a sector-shaped knife blade 25 is located. The thickness of the knife blade is equal to the depth of the recess 24 so that the cutting edge 26 corresponding to the curved part of the blade is situated in the meeting plane of the two sections A and B.

Knife blade 25 is pivoted at 27 in the recess 24. Its extremity 25((1) which extends to the rear of the grappler is pivotally joined to the shaft 28 which is integral with the piston sliding in cylinder 13. On the side facing section B the knife blade has a projection 29 which is arranged to enter a corresponding cavity 30 in section B.

The upper part of section B has, as aforementioned, an offset portion 17 situated in an L-shaped groove of section A. The portion 17 incorporates cylinder 13' connected by the conduit 16' to pump 9. Cylinder 13' is provided with piston 14, which emerges from the cylinder at the lower part of portion 17 and presses on the ledge formed by the horizontal part of the L-shaped groove 17.

When the grappler is at rest, its elements are disposed as shown in FIGS. 3 and 5. In this condition levers 19 and 19 and knife blade 25 are withdrawn in apertures 18 and 18, respectively, and in recess 24 so as to leave free the throat of the grappler. The projection 29 of the knife blade is engaged in the cavity 30 of section B so that any mutual movement between the two sections is prevented. When the recovery operation is started, the grappler is lowered to the bottom in the rest position, and while in such position it is dragged on the bottom until it meets and engages the cable to be recovered.

The cable, being engaged and dragged for a short distance by the grappler, exerts on the latter a force which is registered on board the ship by means of suitable dynamoments associated with the laying winch by means of which the grappler is lowered. A further confirmation of hooking having taken place is provided by two pressure cells 31 and 31' disposed in the throat of the grappler, one in each of the sections A and B. These cells sense the pressure exerted by the cable in the throat and close a switch. Alternatively, the cells can themselves constitute a sealed push-button switch. The closure of the switch which is connected, through a circuit passing through the cables 3 and 3, to a control panel situated on board the vessel, causes the lighting of a signal lamp. The cells 31 and 31 are calibrated in such a way that only a force of a certain value can operate them. In such manner the specific pressure exerted by the sediment of the sea bed remains too low to be able to operate them and only the concentrated force applied by the hooked cable makes their operation possible.

There are two cells because one serves as a check on the other, thereby preventing a force applied fortuitously on only one of them from closing the circuit and being taken as a signal that the cable is hooked.

When the hooking signal is received on the ship and it is confirmed by the dynamometers of the laying winch, the starting switches of motors and 10 are operated on the electric control panel on board the vessel. These motors, in turn, drive the pumps 8 and 8 forcing oil into cylinders 12 and 12', causing movement of the pistons therein and of rods 20 and 20 attached thereto and, therefore, movement of the levers 19 and 19. When levers 19 and 19 are actuated the ends facing the throat of the grappler lower themselves to grip the hooked cable within said throat. In the arrangement shown in the drawings, clamping of the cable occurs with movement of the rods 20, 20' into their respective cylinders.

Pumps 8 and 8 are connected hydraulically to the housing of the motors 10 and 10' so that they suck the oil of the reservoirs through said motors, thus cooling them. In the conduits and 15' are disposed thrust meters 32 and 32' controlling switches 33, 33, both being inserted in such a way that the motors 10 and 10 are started automatically if the pressure in the respective circuit drops below a predetermined level.

Valves 34, 34 prevent return of oil to the pump and therefore any movement of the piston in cylinder 12 or 12 which would lead to accidental unhooking of section C or C (see FIG. 4) of the cable. The unhooking will be effected by actuation of a suitable means (not shown) for discharging the oil.

Once a cable is secured to the grappler by virtue of operation of levers 19 and 19', current is fed to the motor 11 causing pump 9 to operate. Then, through the piston associated with cylinder 13, the knife blade 25 is caused to project. This movement corresponds, as seen in the drawings, to a movement of rod 28 out of cylinder 13.

The tip of the knife blade enters a groove or recess at the forward edge of the hook 7. The groove contains an abutment which acts as a stop against any further advancement of the blade. Then the switch which controls the motor 11' belonging to section B is actuated on the panel on board. This motor, through the pump 9, moves the piston 14' and starts movement of section A relative to section B.

In this way the electric cable suspended in the throat of the hook is cut between the cutting edge 26 of knife blade 25 carried by section A and the cutting edge 26' formed by the edge of the hook of section B. Levers 19 and 19' grip the cable in such a way that after the cut its two ends are still firmly held so that they can be brought to the surface.

Continuing the stroke of piston 14, the two sections A and B separate completely as soon as they have passed the ends of the guides 1-2. The two separated sections continue, however, to maintain their hold on each of the severed cable ends C and C.

In bringing cables 3, 3' on board, two catenaries are formed, extending from the pulley of the cable laying ship. These comprise the grappler cables 3 and 3' and the two branches C and C of the severed submarine cable.

According to need, section A or B can be brought aboard alone with one end of the severed cable. Then the end of a buoy cable can be secured to said section and the latter can be placed again in the sea, thereby fastening it to a buoy. The other section can then be recovered bringing on board the other cable end on which to begin the succeeding repair operation.

What is claimed is:

1. Apparatus for severing and recovering submarine cables comprising a grappler formed from two separable sections, each with a hook-shaped throat portion, said sections being provided with means for separably joining one to the other in side-by-side relationship for relative longitudinal separation and with said throat portions in sideby-side relation with one substantially coextensive with the other thereby to provide an upwardly opening throat for the grappler formed in part by one of said throat portions and in part by the other of said throat portions, individual cable means secured to each of said sections for applying an upwardly directed force on and for manipulating the grappler in a body of water, means carried by each of said sections for gripping a submarine cable 10d god in said grappler throat at spaced portions thereof Within said throat, and means for simultaneously severing said submarine cable and separating said sections, and hence said throat portions, along a common plane.

2. Apparatus according to claim 1, wherein the means for obtaining a grip on said submarine cable comprise a lever in each of said sections pivotally mounted thereon, said levers having one end curved for cooperation with the respective throat portion of each section of the grappler for gripping a submarine cable vise-like therein, the opposite ends of said levers being joined operatively to respective actuating elements in each of said sections.

3. Apparatus for severing and recovering submarine cables comprising a grappler formed from two sections, each with a hook-shaped throat portion, said sections being provided with means for separably joining one to the other in side-by-side relationship for relative longitudinal separation and with said throat portions cooperating to provide a throat for the grappler, individual cable means secured to each of said sections for manipulating the grappler in a body of water, means carried by each of said sections for obtaining an independent grip on a submarine cable lodged in said grappler throat, and means for simultaneously severing said submarine cable and separating said sections along a common plane, comprising a retractable blade carried by one of said sections with a cutting edge disposed, at least when the blade is extended, in said common plane in opposition to a second cutting edge on said other section also in said common plane, means for extending said blade when a submarine cable is lodged in the throat of the grappler, and means for forcibly separating said sections along said common plane so as to cause said cutting edges to approach each other and sever said cable.

4. Apparatus according to claim 3, wherein said retractable blade is provided with means for interlocking engagement with said other section of the grappler when said blade is retracted to preclude premature separation of said sections. V

5. Apparatus according to claim 4, wherein said blade is pivotally mounted on said one section of the grappler in a recess along the side which mates with said other section, said blade being movable by said means for extending same between a first position withdrawn within said recess and a second position extending therefrom across the throat of said grappler, and wherein the side of said blade facing said other section of the grappler is provided with a protuberance which occupies a complemental recess in said other section when the grappler sections are together and said blade is in its first position, and is outside of said recess when said blade is in its second position.

6. Apparatus according to claim 3, wherein said blade is pivotally mounted on said one section of the grappler for movement by said means for extending same between a first position clear of the throat of the grappler and a second position extending from said one section of the grappler across the throat portion thereof, and wherein an abutment is provided near the tip of the throat portion of said one section of the grappler for engagement by said blade in its second position, said abutment being arranged to prevent further pivotal movement of said blade during said severing operation.

7. Apparatus for severing and recovering submarine cables comprising a grappler formed from two sections, each with a hook-shaped throat portion, said sections being provided with means for separably joining one to the other in side-by-side relationship for relative longitudinal separation and with said throat portions cooperating to provide a throat for the grappler, individual cable means secured to each of said sections for manipulating the grappler in a body of water, means carried by each of said sections for obtaining an independent grip on a submarine cable lodged in said grappler throat, and means for simultaneously severing said submarine cable and separating said sections along a common plane, each section of said grappler having on the side opposite said throat portions a reservoir containing hydraulic fluid and elec trically operated fluid pumps, having hydraulic actuators external to said reservoirs for actuating the several said means for gripping the submarine cable and severing same and having conduit means interconnecting said pumps with said actuators, and said individual cable means having electric conductors communicating with an electrical motive element of said pumps for remote energization thereof.

8. Apparatus according to claim 7, wherein said reservoirs are of flattened form and arranged, when the sections of the grappler are united, in parallel relationship for stabilizing the grappler as it is moved through water, the size and shape of said reservoirs being selected such that the center of buoyancy of the grappler is on the reservoir side of the center of gravity thereof.

9. Apparatus for severing and recovering submarine cables comprising a grappler formed from two sections, each with a hook-shaped throat portion, said sections being provided with means for separably joining one to the other in side-by-side relationship for relative longitudinal separation and with said throat portions cooperating to '25 provide a throat for the grappler, individual cable means secured to each of said sections for manipulating the grappler in a body of water, means carried by each of said sections for obtaining an independent grip on a submarine cable lodged in said grappler throat, and means for simultaneously severing said submarine cable and separating said sections along a common plane, each section of said grappler having on the side opposite said throat portions a reservoir containing hydraulic fluid, said reservoirs being of flattened form and arranged, when the grapplers are united, in parallel relationship for stabilizing the grappler as it is moved through water, the size and shape of said reservoirs being selected such that the center of buoyancy of the grappler is on the reservoir side of the center of gravity thereof.

References Cited UNITED STATES PATENTS 3,266,353 8/1966 Gretter 294-66 X 3,319,426 5/1967 Slonczewski 29482 X FOREIGN PATENTS 971,152 9/1964 Great Britain.

LESTER M. SWINGLE, Primary Examiner I. C. PETERS, Assistant Examiner U.S. Cl. X.R. 83-27; 29466 mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3 .516 158 Dated June 2 3, 1970 lnvent flfl l ntonio Fe rrentino It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 line 34, after the word "severed" insert the word --e1ectric;

SIGMED Am .ZE ii? on 2 Q1970 SEAL) .Aueau mm B. 501mm. JR-

Zmward M. Flasher In Gomisaionor or Pamta Melting Officer 

